Messages in this thread |  | | | Date | Fri, 27 Feb 2004 13:50:19 +0000 | | From | Russell King <> | | Subject | Re: Why no interrupt priorities? |
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On Fri, Feb 27, 2004 at 09:31:43PM +0800, Michael Frank wrote: > On Fri, 27 Feb 2004 09:05:48 +0000, Russell King <rmk+lkml@arm.linux.org.uk> wrote: > > On Fri, Feb 27, 2004 at 02:26:31PM +0800, Michael Frank wrote: > >> Is this to imply that edge triggered shared interrupts are used anywhere? > > > > It is (or used to be) rather common with serial ports. Remember that > > COM1 and COM3 were both defined to use IRQ4 and COM2 and COM4 to use > > IRQ3. > > > >> Never occured to me to use shared IRQ's edge triggered as this mode > >> _cannot_ work reliably for HW limitations. > > > > The serial driver takes great care with this - when we service such an > > interrupt, we keep going until we have scanned all the devices until > > such time that we can say "all devices are no longer signalling an > > interrupt". > > > > This is something it has always done - it's nothing new. > > > > Sorry, i think the serial driver IRQ is level triggered :)
That's actually incorrect. Serial devices are (were) connected to the old ISA PICs which are definitely edge triggered.
-- Russell King Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/ maintainer of: 2.6 PCMCIA - http://pcmcia.arm.linux.org.uk/ 2.6 Serial core - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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